Models for the Interplay of Mechanics, Electrochemistry, Thermodynamics, and Kinetics in Lithium-Ion Batteries

We review a broad range of topics related to the interplay of electrochemistry and mechanics in all solid-state batteries. The modeling frameworks that exist in the literature are varied in terms of their sophistication and ability to capture critical observations. Modeling frameworks for diffusion induced stress and fracture due to lithiation swelling and shrinkage in storage materials for the cathodes are well-established along with models for lithium-ion transport in solid electrolytes. Similarly, aspects of the effect of stress on the redox reactions at the Li metal/electrolyte interface are well-understood. These models typically modify Butler–Volmer kinetics but neglect the effect of creep or other plastic deformations of the metal electrode on the interface kinetics. Nevertheless, they successfully describe the roughening of the metal electrode/electrolyte interface during deposition or plating. By contrast, Butler–Volmer kinetics accounting only for the interfacial stress are unable to predict voids that have been observed to form in the metal electrode and we discuss a hypothesis that creep deformation of the metal electrode has a more fundamental effect on the redox reactions. Similarly, models for the nucleation and growth of lithium filaments in solid electrolytes are also inconsistent with recent observations which suggest that cracks in solid electrolytes are only partially filled with lithium metal. We conclude by summarizing aspects of the interplay of electrochemistry and mechanics in all solid-state batteries that are well-understood and areas where significant open questions remain.